Toners for developing electrostatic images to be used for thermal fixing systems are required to be not fused to a heat roll even at high fixing temperatures (hot offset property) and to be capable of being fixed even at low fixing temperatures (low-temperature fixing property). Generally, the hot offset property and the low-temperature fixing property of a toner is prone to be mutually contradictory properties. As a toner having well balanced hot offset property and low-temperature fixing property, a toner containing two polyesters different in glass transition temperature as resins for toner is disclosed (see, for example, patent document 1).
Patent document 1: JP 2005-221986 A